The use of nitro-substituted para-phenylenediamines as dyes for keratinaceous substrates is well known. See J.F. Crobett, The Chemistry of Synthetic Dyes, Vol. V., K. Venkataraman, ed., Academic Press., New York, p. 475 (1971). U.S. Pat. Nos. 3,591,638; 4,470,826 and 4,668,236, as well as Canadian Patents 806,152 and 935,094 describe the preparation and use of these types of dyes.
Hair dye chemists have long searched for substitutes for some of the simpler 2-nitro-p-phenylenediamine (2-NO.sub.2 -PPD) derivatives, e.g. 2-nitro-p-phenylenediamine, because of poor stability in cosmetic formulations and poor washfastness. However, many of the compounds suggested as substitutes for 2-NO.sub.2 -PPD do not posses the unique bright orange-red color and, therefore, represent poor substitutes. Indeed it has been shown that substitution on the amino group in the 2-nitro-p-phenylenediamine series gives absorption maxima at considerably longer wavelength. The color of these nitro dyes is shifted towards red-violet or violet rather than orange-red (See J.F. Corbett, J. Soc. Cosmet. Chem., 35, 297, (1984).
The basic structure of the target compounds is 3,4-dihydro-2H-1,4-benzoxazine. A number of approaches to the synthesis of this system have been reported since 1889.
Work on the synthesis of 1,4-benzoxazine was reported by Knorr at Berichte der Deutchen Chemischen Gesellschaft (Ber.) 22, 2085 (1889) and Ber. 55, 3818 (1922). Heating 2-(2-chloroethylamino)phenol 6a with alkali gave 1,4-benzoxazine 7a. ##STR2##
Compound 7a was also synthesized from 2-(2-hydroxyethylamino)-anisole 8a under acidic condition using hydrochloric acid at 160.degree.-180.degree. C. (A. Fairbourne and H. Toms J. Chem. Soc., 119, 2076 (1921)). ##STR3##
Hill and Ramage reported at J. Chem. Soc., 3709 (1964) a convenient synthesis of 7-methoxy-1,4-benzoxazine from 2-amino-5-methoxyphenol 9a. Compound 9a reacted with chloroacetyl chloride in acetone to give 2-chloroacetamido-5-methoxy phenol 10a. An intramolecular cyclization of 10a with aqueous sodium hydroxide produced 7-methoxy-3-oxo-1,4-benzoxazine 11a, which upon reduction with lithium aluminum hydride in THF resulted in the formation of 7-methoxy-3,4-dihydro-2H-1,4-benzoxazine 12a. ##STR4##
In U.S. Pat. Nos. 3,690,810 and 3,817,995, L'Oreal reported the synthesis of 6-hydroxy (or amino)-3,4-dihydro-2H-1,4-benzoxazine 15a (or 19a) as an oxidation coupler. Reaction of 2-amino-4-methoxyanisole 13a with 2-bromoethanol and calcium carbonate in water gave compound 14a. Subsequent cyclization of 14a with HBr afforded 15a. ##STR5##
Treatment of 2-methoxy-5-nitroaniline 16a with 2-chloroethyl chloroformate and calcium carbonate in dioxane afforded the carbamate 17a. Rearrangement of 17a followed by an intramolecular cyclization by action of potassium hydroxide in ethanol led to the formation of 6-nitrobenzoxazine 18a. Reduction of 18a with iron in acetic acid produced 6-aminobenzoxazine 19a. ##STR6##
Recently, two procedures have been reported for the synthesis of 1,4-benzoxazine systems by the use of an intramolecular reductive cyclization of nitroketones. Condensation of 20a with benzylamine afforded phenoxy alcohol 21a, which was oxidized with Jones reagent to give the nitroketone 22a. Reductive cyclization of 22a with Raney Ni in ethanol afforded 23a. This was reported in Synthesis 660, 1974 by S.P. Gupta et al. ##STR7##
Similarly, compound 24a was converted to 25a by catalytic transfer hydrogenation using NaH.sub.2 PO.sub.2 as hydrogen donor and 5% Pd-C as catalyst in a two phase system (H.sub.2 O/THF). See P. Battistioni et al, Synthesis 220 (1979). ##STR8##
Coudert et. al reported in Synthesis, 541 (1979) a new synthetic approach to 1,4-benzoxazine using solid-liquid phase-transfer catalysis. Cyclocondensation of ortho-hydroxycarboxanilides 26a with 1,2-dibromochane in the presence of powdered NaOH and Aliquat 336 in CH.sub.3 CN/CH.sub.2 CCl.sub.2 proceeded in high yield to give 27a which, with KOH in MeOH, afforded 28a. ##STR9##
The N-substituted 1,4-benzoxazine 30a was obtained by a photochemical cyclization of 29a with irradiation (100 W high-pressure mercury lamp). See K. Mutai et al Tet. Letters, 931 (1978). ##STR10##
In U.S. 4,552,951, an azo dye was prepared using benzomorpholine couplers and having one or two cinnamoyl substituents. At column 2, lines 37 and 57 , NO.sub.2 and NH.sub.2 are disclosed as substituents on the benzene ring of the bicyclic benzoxazine system.
Chemical Abstracts 106: 138457t (EPO Publication 196,570) discloses herbicidal compositions containing benzoxazine derivatives.
Chemical Abstracts 106: 102305c recites 7,8-difluoro-3,4-dihydro-3-methyl-2H-1,4-benzoxazine as a herbicide.
All publications cited herein are hereby incorporated by reference, unless otherwise stated.
While various of these references show compounds which are similar to the structural formulas recited herein, none of them actually teaches the use of applicants' compounds as dyes.